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O: Fachverband Oberflächenphysik
O 102: Graphene: Interaction with the Substrate (HL jointly with DY, MA, O, TT)
O 102.4: Vortrag
Freitag, 4. April 2014, 12:00–12:15, POT 081
Towards superlattices: Lateral bipolar multibarriers in graphene — •Martin Drienovsky1, Franz-Xaver Schrettenbrunner1, Andreas Sandner1, Ming-Hao Liu2, Fedor Tkatschenko2, Klaus Richter2, Dieter Weiss1, and Jonathan Eroms1 — 1Institut für Experimentelle und Angewandte Physik Universität Regensburg — 2Institut für Theoretische Physik Universität Regensburg
We report on transport properties of monolayer-graphene (MLG) with a laterally modulated charge carrier density profile. For that we employed a planar back gate and striped top gate electrodes of 25 nm width and a spacing of 100 nm up to 200 nm, separated from the MLG by an Al2O3 dielectric. Tuning of top and back gate voltages gives rise to multiple potential barriers and wells, enabling the investigation of resistance either in the unipolar or the bipolar transport regime. In the latter pronounced single- and multibarrier Fabry-Pérot (FP) resonances are observed. The experimental data of different devices with alternating numbers of top gate stripes and pitch, taken at different temperatures, is consistent with a ballistic transport calculation, employing a realistic potential profile, extracted from classical electrostatic simulation combined with the quantum capacitance model. The origin of resistance oscillations in our multibarrier graphene system can be explained in the FP-picture, without resorting to an artificial band structure.